After every game, Adam Hoge reviews the film and highlights the best and worst performances while also providing some observations.

(CBS) The review of Sunday’s 40-32 loss to the Detroit Lions reconfirmed exactly what Marc Trestman and Jay Cutler said after the game: the quarterback’s four turnovers were the difference in the game.

Of course, Jay Cutler wasn’t the only problem, as he wasn’t on the field while Reggie Bush was busy slicing up the Bears’ defense for 139 rushing yards.

The Bears’ defensive game plan as a whole was interesting. It wasn’t at all surprising that they only blitzed six times, but it was surprising how much nickel they played.

The Bears were in their nickel package for 45 of 67 defensive snaps. As a result, middle linebacker D.J. Williams only saw 22 plays, while nickelback Isaiah Frey was on the field for 45.

The lack of playing time for Williams is interesting as it was the second game in a row he was on the field for 28 or less plays, after playing 44 in each of the first two games. It’s not that Williams is playing poorly — in fact, I have him tied with James Anderson for the fourth-highest cumulative defensive grade this season — it’s just the scheme the Bears have been forced to play the last two weeks. But it still begs the question: Should the Bears make a concerted effort to get their middle linebacker on the field more?

Despite the limited playing time, Williams earned my second-highest defensive grade Sunday, behind only Julius Peppers. You knew the Bears were going to sit back a little bit more this week in an effort to stop Calvin Johnson, but did they sacrifice too much with the amount of nickel they played? To the Bears’ credit, Johnson was held to just four catches on 10 targets, but the Lions also took advantage of the Bears only keeping six guys in the box as much as they did.

“We definitely felt like that was an area we could take advantage,” Reggie Bush said after the game. “When we have them in nickel — their nickel personnel — and there’s six guys in the box, we’ve got to take advantage of that.”

The Lions did. Especially on Bush’s 37-yard touchdown run, when the Lions saw nickel and claimed they knew what was coming.

“It was a play that, honestly, we have been working in practice all week, knowing that they were going to blitz us,” Lions quarterback Matthew Stafford said. “Instead of getting out of it, we just ran right into it. (Center Dominic Raiola) made a great call up front. Pettigrew had a great block. We sealed off the backside and then Reggie did the rest.”

With Williams off the field, Frey blitzed from the blindside edge, but tight end Brandon Pettigrew picked him up. Nose tackle Nate Collins “scoop” stunted the opposite A-gap (rushed the opposite shoulder of the center he was lined up on) and Raiola pushed him aside to right guard Larry Warford before getting to the second level. That’s where Raiola met Lance Briggs, who was slow to fill the other A-gap, leaving a large hole up the middle for Bush. From there, Bush did the rest, leaping over Major Wright’s tackle attempt and outrunning Charles Tillman and Tim Jennings to the end zone.

One can only wonder if the Bears would have had more success against Bush if Williams was on the field more. In his limited snaps, I had Williams down for two above-average stops, one rare-level stop and zero negative plays.

Of course, pick your poison. Had the Bears played more base 4-3, Calvin Johnson may have had a bigger game, especially with cornerback Charles Tillman limited.

To be fair, the Bears played much better all around in the second half without deviating from their original game plan — the execution was just better.

But keep an eye on D.J. Williams’ playing time going forward.

Let’s get to the grades:

Five Highest Grades

DE Julius Peppers – He’s back. Peppers had a monster game, netting the highest overall individual grade of any Bears player this season. I didn’t have the defensive end down for a single negative play and he consistently pushed the tackles backwards, collapsing the pocket. To the Lions’ credit, they ran a lot of short drops and quick throws to negate the pressure, which made the Bears’ defensive line look a lot worse than it really was.

WR Alshon Jeffery – Despite his drop in the end zone, Jeffery still tied with Matt Slauson for the second-highest net grade. He made three elite-level catches, using his size to go up and get the ball while fighting off a defender. Jeffery also took out two defenders with one block on Matt Forte’s 53-yard touchdown run.

LG Matt Slauson – With all the talk about Kyle Long and Ndamukong Suh, Slauson kept Nick Fairley quiet. Fairley was credited with two quarterback hurries, but only one came on Slauson and that was the left guard’s only negative play of the game.

LB D.J. Williams – I mentioned the middle linebacker’s high level of play before and it’s worth mentioning that he started off as the second linebacker in nickel sets before getting hurt in training camp. Maybe the Bears should think about getting Williams some nickel reps during games to get him on the field more. The problem is, James Anderson is playing pretty well too.

RB Matt Forte – Just a solid, productive all around game for the Bears’ running back, who was on the field for 72 of 73 offensive snaps.

Five Lowest Grades

LB Lance Briggs – This would be the definition of how tackles can be a misleading stat. Briggs led the Bears Sunday with 13 combined tackles, but he also graded out the lowest in my review. Many of his tackles came on short passes that he was slow to react to and he was blocked out of plays way too many times, including on Bush’s 37-yard touchdown run.

QB Jay Cutler – It should be noted that Cutler tied Peppers and Slauson for the highest amount of above-average plays, but the negatives were just too much Sunday. It wasn’t just the turnovers. He missed Martellus Bennett in the end zone on a drive that ended with a field goal and his worst pass of the day may have been the duck he threw five yards short of Bennett when he was wide open in the middle of the field on the first play of the fourth quarter.

S Chris Conte – The safety had a rough day tackling. Simple as that.

RT Jordan Mills – Mills wasn’t horrible, but he had trouble in the fourth quarter and many of Cutler’s scrambles came as a result of the pressure from the right side.

S Major Wright – I had Wright down for more missed tackles than Conte, but he also made a few good plays throughout the game — including grabbing an interception and saving a touchdown on an open field tackle on Reggie Bush in the first half. Unfortunately, he was the guy who Bush later hurdled on his 37-yard touchdown run.

Other Observations

– The Bears hardly pulled their guards at all, something they did a lot in the first three games. This was likely due to the Lions’ wide-9 technique, which forces the guards to stay home to block Suh and Fairley.

– Michael Bush was only on the field for two plays, but one of those plays was Matt Forte’s 53-yard touchdown run. Bush lined up as a fullback and Cutler faked the handoff to him before pitching it back out to Forte.

– Nate Collins had an up-and-down day filling in for Henry Melton. Collins was mostly at nose tackle with Stephen Paea getting most of his work in the three-technique. I had Collins down for seven negative plays, but he also made some nice stops, including a big 3rd-and-1 stuff early in the game that held the Lions to the field goal.

Adam Hoge covers the Bears for CBSChicago.com and is a frequent contributor to 670 The Score. Follow him on Twitter at @AdamHoge.